The present invention relates to a wood-type golf club head, more particularly to a hollow structure having a specific configuration capable of improving the directional stability of struck balls.
As well known in the art, if a golf club head hits a ball off the sweet spot towards the toe or heel, then the club head is rotated around the vertical axis passing through the center of gravity of the club head. Such a rotational motion gives the ball an unfavorable sidespin, and the ball deviates from the target trajectory.
Therefore, in order to decrease the rotational motion on off-center shots and thereby to improve the directional stability of the struck balls, there have been made efforts to increase the moment of inertia of the club head around the vertical axis passing through the center of gravity of the head (hereinafter, lateral moment of inertia). For that purpose, the weight of the club head is increased, the depth of the center of gravity of the head from the club face is increased, and/or the distance of the center of gravity from the clubshaft center line is increased.
However, if the club head weight is increased, the swing balance becomes heavy. If the distance of the center of gravity from the clubshaft center line is increased, the moment of inertia around the clubshaft center line is increased. In either case, the club head becomes hard to rotate and as a result, it is difficult to square the club face at impact. In other words, the club face can not return to the addressed square position at impact, and the balls tend to become slice shots. Such tendency is especially remarkable in the case of golfers who can not control club heads during swing very well such as beginners and intermediate golfers. Further, according to conventional designing, if the depth of the center of gravity is increased, the distance of the center of gravity is also increased, and the same problem arises.